The field of Computational Intelligence (CI) covers all sorts of techniques for subsymbolic (numerical) knowledge processing, such as the well known Fuzzy Logic (FL), Neural Networks (NN), and Evolutionary Algorithms (EA) as well as other approaches with lesser dissemination. Although CI techniques are widely in use, there still exists a large gap between theory and application. To close this gap the Collaborative Research Center (SFB) 531 has been founded at the University of Dortmund in 1997 as an interdisciplinary research institute. It is financially supported by the Deutsche Forschungsgemeinschaft (DFG). The scientific goals of the SFB are the investigation and improvement of the foundations, applications, as well as combinations of CI methods.